Fan equipment



Aug- 24, 1965 R. A. wAsSQN ETAL y 3,202,342

FAN EQUIPMENT I Filed Jan. 8, 1964 2 Sheets-Sheet 1 /MMSMW llg- 24, 1965 R. A. wASsoN ETAL FAN EQUIPMENT 2 Sheets-Sheet 2 Filed Jan. 8, 1964 l :Wim

@ngi/2 United States Patent() 3,202,342 FAN EQUlPli/IENT Robert A. Wasson and Sewell H. Downs, Kalamazoo, Mich., assignors to Ciarage Fan Company, Kalamazoo, Mich., a corporation of Michigan Filed Jan. 8, 1964, Ser. No. 336,434 12 Claims. (Cl. 230-1'17) This application is a continuation-in-part of our copending application Serial No. 130,049, filed Aug. 8, 1961, now Patent No. 3,122,307. The invention disclosed in this application relates in general to a combination fan construction including a housing structure defining a pair of coaxial, annular passageways and an impeller assembly including a centrifugal impeller and an axial flow impeller connected to each other and rotatably supported upon the housing structure for effecting the flow of gas in an axial direction simultaneously through the two passage- Ways. A fan construction containing a dual impeller of this type is disclosed in our co-pending application Serial No. 130,049.

Generally speaking, the preliminary remarks set forth in Serial No. 130,049 with respect to the problems found in the prior art structures and the advantages of applicants invention over such prior art structures also apply to the `fan construction disclosed herein. However, further experimental work on, and further testing and actual use of, the first model of applicants invention disclosed in Serial No. 130,049 lead to further improvements in the earlier fan construction.

By way of example, it was found that the axial iicw or propeller blades disclosed in Serial No. 130,049 developed, in the vicinity of the propeller blades, localized circulations of gas which reduced the performance of said blades, hence, the performance of the axial flow impeller. These circulations were materially reduced by modifying the propeller blades as set forth in the following specification.

However, in further testing, it was found that there existed at the tips of the modied propeller blades a condition of turbulence and reverse gas flow which, if eliminated, could be expected to improve materially the performance of the axial ow impeller or wheel. It is of importance to note that reduction of turbulence adjacent the tip of the axial flow impeller could also be expected to lower the level of sound produced by the axial flow wheel for well-known reasons.

The addition of flange means at the inlet end of the outer passageway was found to improve somewhat the ow pattern of the gas adjacent the outer casing and, hence, adjacent the tips of the axial flow blades. However, the most dramatic improvement in the turbulent condition adjacent the tips of the axial flow blades and, moreover, the virtual elimination of the reverse flow pattern adjacent the blade tips was produced by placing vanes of relatively short axial length adjacent the downstream sides of the axial ow blades and near the tips thereof.

It was found, particularly for small installations, that the impeller assembly, including the centrifugal impeller and the axial flow impeller, could be mounted upon the shaft of the motor used to rotate the impeller assembly.

It was also found that inlet -vanes could be advantageously used in controlling the flow of air into either or both ofthe inner and outer passageways through which the gas was being moved by the centrifugal impeller and the axial flow impeller, respectively. The effects produced by the inlet vanes in the passageway leading to the centrifugal impeller were, in substance, somewhat anticipated from the previous use of inlet vanes with conventional centrifugal fans. However, the inlet vane control used with the axial flow impeller produced some unexpected results. With the vanes positioned in one angular position transverse of a radius of the impeller, the performance of the axial flow impeller was increased. On the other hand, movement of the inlet vanes into transverse positions with respect to the radius of the impeller in the opposite direction produced a reduction in the capacity of the axial flow impeller.

Accordingly, the objects of the invention have been to provide:

(il) An improved combination fan construction wherein a centrifugal impeller is connected to and driven simultaneously with an axial flow fan so that a single unit having coaxial exhaust and supply passageways can be effectively and efficiently used without high and/or noisy tip speeds, which can be conveniently and acceptably installed adjacent the air space which it serves, which can be manufactured at a cost competitive with dual propeller fan constructions for the same or similar purposes, and which is capable of producing more efficient performance and developing greater capacities than existing, competitive constructions.

(2) An improved fan construction, as aforesaid, wherein the supply passageway is on the outside and a propeller fan is located therein to use the axial flow fan Where it is most efficient (i.e., of largest diameter) and its relatively smaller capability for developing static pressure will not adversely affect the operation of the unit; and wherein the centrifugal impeller is used in association and communication with the inner and smaller exhaust passageway Where the higher static pressures are desired.

(3) An improved fan construction, as aforesaid, wherein the obstruction of the discharge of exhaust gases from the centrifugal impeller is reduced to a point far below that which is normally encoutered by the discharge of exhaust gas from an axial flow impellerjused under the same circumstances, due primarilyto the: normal characteristic of the centrifual impeller to discharge radially; and wherein the capacity of the centrifugal impeller is so much greater than the axial flow impeller normally used in the same location that the combination fan construction can be satisfactorily used for Ventilating not only the air space adjacent the unit but also at substantial distances therefrom and connected thereto by substantial lengths of duct work.

(4) An improved combination fan construction wherein the performance of the axial flow impeller thereof has been improved substantially over that of the axial flow impeller in Serial No. 130,049, and wherein the ccntrol over the capacity of said axial flow impeller has been improved.

(5) A fan construction, as aforesaid, which is capable of performing in all other respects at least as Well as the fan construction disclosed in Serial No. 130,049 and which can be produced, therefore, more economically for accomplishing the same Work.

(6) A fan construction retaining all of the advantages of the fan construction disclosed in Serial No. 130,049. Other objects and purposes of this fan construction will become apparent to persons familiar with this type of equipment upon reading the following descriptive material and examining the accompanying drawings, in which:

FIGURE 1 is a side elevational view of the combination fan construction embodying the invention.

FIGURE 2 is a sectional view taken along the line II-II in FIGURE l.

FIGURE 3 is a sectional view taken along the line III- III in FIGURE 2.

FIGURE 4 is a sectional View taken along the line IV-IV in FIGURE 2.-

FIGURE 5 is a sectional View taken along the line V-V in FIGURE 4.

FIGURE 6 is a fragment `of FIGURE 2 illustrating a modified construction.

FIGURE'7 is a sectional view taken along the line VII-VII in FIGURE 6.

FIGURE 8 is a sectional view taken along the line VIII- VIII in FIGURE 6.

For convenience in description, the terms upper, lower and Words of similar import will have reference to the fan construction as shown in FIGURES l and 2 which disclose one normal position of its operation. The terms innerj outer and derivatives thereof will have reference to the geometric center of said fan construction and parts thereof.

GENERAL CONSTRUCTION The objects and purposes of the invention, including those set forth above, have been met by providing a combination fan construction comprised of a housing having wall structure defining inner and outer, substantially coaxial passageways and a dual impeller assembly rotatably supported Witihn the housing for effecting simultaneous, preferably counteraxial, flow of gas, such as air, through said passageways. The dual impeller assembly is comprised of a centrifugal impeller or wheel, which has an inlet communicating with the inner passageway, and another impeller, such as an axial ow fan, located in or adjacent to the outer passageway, whereby rotation of said dual impeller assembly can effect movement of air through the inner passageway in one direction and movement of air through the outer passageway in the same or opposite direction. Suitable means are provided for effecting rotation of said dual impeller assembly, and baffling means is usually provided for separating the ambient source of air supply from the exhausted air.

The combination fan of the invention is especially suited for mounting upon a horizontal wall, such as a roof, for exchanging the gas, such as air, in the space below said wall or roof including space connected to said fan unit by ducts and disposed at substantial distances from the space directly below the unit. However, said combination fan construction can also be mounted with equal effectiveness upon a substantially vertical wall for the same or similar purposes.

DETAILED DESCRIPTION The combination fan construction 10 (FIGURE 1), which illustrates a preferred embodiment of the invention designed for roof mounting, is comprised of an impeller housing 11 in which a dual impeller assembly 12 (FIG- URE 2) is supported and rotated by a drive mechanism 15 including a motor 13 and the shaft 43. The motor 13 and part of the drive mechanism 15 may be supported upon an upper wall of the housing 11 beneath and within the cover 14. The housing 11 may be supported upon a base 16 which in turn is mounted, for example, upon the roof 17 above the space being serviced by the fan construction 10.

The base 16 is preferably, but not necessarily, a substantially flat and rectangular structure having a horizontal top wall 18 and a substantially vertical flange extending partially or completely around and downwardly from the perimeter ofthe top wall 18. Additional, intermediate support elements, such as that indicated at 22 in FIGURE 2, may be provided between the roof 17 and top wall 18 for supporting purposes, if necessary. The top wall 18 has a central opening 23 and may be provided with an integral circular flange 24- around said opening for reasons appearing hereinafter.

The base 16, the impeller housing 11, the dual impeller 12 and many of the parts associ-ated therewith are preferably, but not necessarily, fabricated from relatively stiff and durable material such as sheet metal, bar stock, metal castings and the like, which are connected together by conventional devices such as screws, rivets and/ or welding.

The impeller housing 11 (FIGURE 2) includes an outer cylindrical casing 26, the lower end of which is 4 snugly sleeved around and secured to the flange 24. In this embodiment, the cylindrical casing 26 is axially upright, is open at its upper and lower ends, and has an integral, annular ange 25 which extends radi-ally outwardly from the upper end of said casing 26.

An inner, cylindrical wall member 27 is concentrically disposed within and supported upon the casing 26 by the plates or brackets 28. The outer casing 26 and cylindrical wall member 27 define between them an outer, annular passageway 29 which communicates between the upper end of the casing 26 and the central opening 23 in the base 16.

The roof 17 (FIGURE 2) is preferably provided with a circular opening 32 which is coaxial with and slightly larger than the central opening 23 in the top wall 1S, A cylindrical sleeve or duct 33 may be disposed within the circular roof opening 32 so that it extends toward and adjacent the top Wall 18. Means, such as a cylindrical duct 34, may be sleeved upon the lower end of the wall member 27 in a conventional manner for communication between the lower end of the wall member 27 and a selected air space within the zone below the roof 17. Thus, the two cylindrical ducts 33 and 34 define, in effect, a continuation of the outer passageway 29.

The bearing assembly 36 includes a pair of coaxial bearings 37 and 38, which are supported within the opposite ends of a cylindrical tube 39. Said tube 39 is supported coaxially within and upon the cylindrical wall member 27 by support brackets 42 which are secured to and extend diagonally between the tube 39 and wall member 27, so that the length of the tube 39 can be minimized. The upper end of the bearing assembly 36 extends into the inlet of the centrifugal wheel 46 and rotatably supports the impeller shaft 43 coaxially with the wall member 27. The wall member 27 defines an inner passageway 44 which communicates at its lower end with the cylindrical duct 34. Means, such as a pair of set collars S6 and 57, are secured to the shaft 43 adjacent the upper and -lower ends, respectively, of the bearing assembly 36 to prevent axial movement of the shaft 43 with respect to said bearing assembly.

The dual impeller assembly 12 (FIGURE 2) includes the centrifugal fan wheel 46 which may be of any convenient type. In this particular embodiment, and for illustrative purposes only, said wheel 46 is comprised of a backplate 47 supported upon and secured to a hub 4S which is mounted upon the shaft 43 above the bearing assembly 36 and is secured to said shaft 43 by means including a set screw 49. The wheel 46 has a plurality of blades 52 secured `at `one end `of each to said backplate 47 and at the other end of each to an annular rim or flange 53 on the sleeve 61. The rim 53, which defines a wheel inlet opening 54, converges toward the cylindrical wall member 27.

A cylindrical sleeve or inlet pipe 61 is coaxially secured to or integral with the rim 53, preferably at its inner edge, and extends downwardly therefrom to the upper end `of the wall member 27. In this particular embodiment, the sleeve 61 is of somewhat larger diameter than the Cylindrical wall member 27. However, this specific arrangement may be varied to meet the specific requirements of a particular installation.

The dual impeller assembly 12 also includes an outer impeller 62 (FIGURE 3) which is an axial flow fan. The lower end of the sleeve 61 serves as part of the fan 62 in that it supports a plurality of propeller blades 64 at uniform intervals therearound. Said blades 64 extend radially toward the outer casing 26, preferably near the upper end thereof, and each blade is secured to the sleeve. 61 by single screw means 66 so that said blades can be adjusted :around their lengthwise axes, that is, around*- radii of the sleeve 61.

The blades 64 of the outer impeller 62 (FIGURES 2y and 3) are preferably tapered toward their tips and they' ably have airfoil shapes and each blade has a flange 63 at its root end which engages the peripheral surface of the sleeve 61. Each screw means 66 (FIGURE 4) may include a stud 67 which is welded to the ilange 63 and extends through a suitable opening 65 in the sleeve 61 where said stud is engaged by a nut 68 to hold the blade in a selected position on said sleeve. The blades 64 are arranged so that rotation of the dual impeller assembly 12, which effects the proper radial discharge from the centrifugal wheel 46, will cause the outer impeller 62 to move air or gas downward through the outer passageway 29 while gas is being moved upwardly through the inner passageway 44 by the centrifugal wheel 46.

An annular baliie assembly 74 is spaced upwardly from the upper end of the outer casing 26 and is supported coaxially thereon by a plurality, here three, of upright support posts 76, each of which is secured to the outer casing 26 by a channel-shaped member 79. The baille assembly 74 includes a lower baiiie ring 75 which is mounted between its radial edges upon the support posts 76. The radially outer portion of the baie ring 75 curves from said support posts 76 downwardly and outwardly to terminate in a substantially vertical tiange 77 which preferably telescopes slightly and is spaced radially outwardly from the upper end of the outer casing 26, including the flange 25. The baffle ring 75 cooperates with the upper end of the casing 26 to define an inlet passage 78 which cornmunicates between a supply of ambient air and the upper end of the outer annular passageway 29.

The baffle assembly 74 includes a deflector ring 84 which is concentrically supported upon and secured to the upper surface of the baffle ring 75 near its flange 77. The ring 84 extends slightly downwardly and then curves upwardly and outwardly to deiiect the gas discharged from the wheel 46 upwardly away from the inlet passage 78.

The upper wall of the impeller housing 11 is supported upon the upper ends of the posts 76 and spaced up- Wardy from the annular bafiie assembly 74 a distance about equal to the wheel width, adjacent the wheel 46. The diameter of the upper wall 20 is preferably greater than the diameter of the centrifugal wheel 46, which it covers, and is somewhat less than the diameter of the baffle assembly 74. The upper wall 2t) has a central opening 83 through which that portion of the hub 48 containing the set screw 49 extends so that said set screw is accessible.

The motor 13 (FIGURE 2) is secured upon a motor pedestal 70 by means of the bolts 69, and said pedestal 7i) is secured upon the upper wall 2t) by bolts 71 so that the motor shaft 88 extends vertically downwardly from the motor 13. The motor cover 14 includes a downwardly diverging skirt 72 which is spaced from and is of smaller diameter than the lower baffle ring 75. Said skirt 72 is preferably secured to the lower edge of the cover 14 and is intended to protect the wheel 46 from inclement weather.

A driven pulley 87 is mounted upon the upper end of the shaft 43 adjacent the hub 48 and secured thereto, and a driving pulley 91 is mounted upon the motor shaft 88. The pulleys 87 and 91 are interconnected by one or more belts 93, whereby rotation of the motor shaft 83 effects rotation of the dual impeller assembly 12.

A plurality of guide vanes 95 (FIGURE 2) are rigidly secured to and extend inwardly from the casing 26 adjacent the downstream side of the axial flow fan 62. As shown in FIGURES 4 and 5, the guide vanes 95 are curved at their upstream ends substantially around a radius of the casing 26 and in a direction opposed to the direction of movement of the blades 64 when the impeller assembly 12 is normally rotated by the drive mechanism 15. As shown in FIGURES 2 and 5, the downstream end portions of the guide vanes 95 are substantially fiat and, as shown in FIGURE 8, these end portions define planes perpendicular to the rotational plane of the impeller 62 and extending substantially diametrically of the casing 26. That is, the guide vanes 95 are arranged to receive the air which is moved away from and by the axial iiow fan 62, so that the circular components of such movement are removed and the air thereafter liows straight through the outerpassageway 29 with a minimum of turbulence and frictional loss.

The guide vanes have been found to eliminate the reverse tiow of gas which exists adjacent the tips of the blade 64 when the guide vanes 95 are not present. As shown in FIGURES 2, 3, 4, 6 and 8, the vanes 95 extend inwardly from the casing 26 a distance less than half the radial distance between the casing 26 and the wall mem.- ber 27 or sleeve 61. The principle function ofthese vanes is the control over the gas near Ythe tips of the blades, as stated above. Said guide vanes 95 have flanges 96 through which rivets 97 may extend for securing said guide vanes 95 to the casing 26. In one embodiment, the guide vanes 95 were uniformly spaced from each other at intervals roughly corresponding to the center line distance between adjacent blades 64. However, variations of this spacing between guide vanes are expected.

A cylindrical wire` screen 98 (FIGURE 2) is advan-` tageously mounted between the lower baiiie ring 75 and the upper wall 20 so that it encircles the support posts 76. A similar cylindrical screen 99 extends between the lower `baiile ring 75 and the peripheral edge of the flange 25 so that it encircles the support posts 76. The screens 98 and 99 block the entry of birds and the like into` the housing 11. The clamps 101 and 102 are provided to secure the screens 98 and 99, respectively, to the support posts 76.

A duct or trunk 103 (FIGURE 2) may be mounted upon the lower surface of the roof 17 so that it encircles the duct 34 and communicates with the lower end of the passageway 29, which is defined by the duct 33. Thus, either the passageway 29 or the passageway 44 can be connected to remote points in the zone being serviced by the fan construction 1t).

OPERATION With the fan construction 10 installed on the roof 17, for example, the cylindrical wall member `27 will normally be connected to a duct 34 which will communicate with the zone from which gas or air is to be exhausted. Also, the outer casing 26 may be connected by the duct 33 to a trunk 103 whereby the air moved downwardly through the casing 26 will be discharged into zones spaced a substantial distance from the fan construction 10.

Upon energizing the `motor 13, the impeller 12 is rotated in a directionwhereby gas is caused to move upwardly through the inner passageway 44 within the wall member 27, sleeve 61 and inlet opening 54 in the centrifugal wheel 46, and is then discharged in a substantially conventional manner radially outwardly by the blades 52 of the wheel 46, so that it discharges between and radially beyond the skirt 72 and deflector ring 84. As stated above, the deliector ring 84 causes the discharged air to be deflected away from the inlet passage 78, which deiection will often be augmented by the normal convection currents inthe ambient air. The outer irnpeller 62 will, at the same time, draw air through the inlet passage 78 and move it downwardly through the outer passageway 29 into the zone in communication with the duct 33 or trunk 103.

Although the drawings and much of the description are specific to a fan construction 1t) mounted upon and above a roof, an inverted installation is fully contemplated, in

whichthe fan construction is supended from the underside of fa roof so that the inlet and exhaust functions of the outer and inner impellers would be reversed. In such an installation, appropriate baiiles and ducts would be provided. It will also be seen that no material changes, if any, would be required to mount the fan construction 1t) upon either the inside or outside of a vertical wall in j substantially the same manner as described above with respect to a roof. However, it might be necessary to provide additional support for the motor 13 and motor cover 14, because of their lateral overhang. l

It is common knowledge that the most eflicient portion of a propeller type of axial flow fan is usually in the region thereof spaced a substantial distance from the hub, and preferably including that portion thereof near the periphery of the propeller fan. Accordingly, the impeller 12 has been designed with this fact in mind. In the first place, the propeller fan is located in the outer one of the two passageways. Secondly, the performance of the blades 64, which is better than the performance of the corresponding blades in the earlier construction, has been further improved by adding the guide vanes 95. That is, the impeller 62 has been arranged so that its peripheral portion will operate with a minimum of obstruction and frictional losses.

It is also very well known that a centrifugal fan can operate `substantially at full capacity ,and a peak performance where the inlet duct communicating with the inlet of the fan has a diameter about equal to the opening in -the inlet side of the wheel. Thus, instead of using a low efficiency, low-pressure type of propeller or -axial flow fan in the inner passageway 44, applicants have arranged to use a relatively high efficiency and high-pressure, centrifugal wheel, which greatly enhances the performance of the total fan construction, while maintaining an over-all size, capacity and cost which are entirely competitive with existing dual fan constructions utilizing two propeller fans.

It will also be seen that, where the fan construction 10 -is used in a closed system, any tendency for the propeller fan portion of the impeller 12 to be unable to meet the full requirements for a supply of air will be yovercome by a negative pressure condition created in the system by the centrifugal fan wheel which will actually induce the flow of air through the outer passageway 29 and thereby augment the operation of the propeller fan portion of the impeller.

It has been found that, by controlling the diameters yof the sleeve 61 and the adjacent end portion of the wall member 27, the leakage of air or gas between the sleeve 61 and the wall member 27 can be carefully controlled. This condition is aided by the fact that the lspace between the member 27 and sleeve 61 is downstream of the propeller fan and upstream of the centrifugal fan. Where contamination of the supply air by the exhaust air within the fan construction 10 is undesirable, the sleeve 61 will preferably be larger than, and slightly overlap, the adjacent end Iof the wall member 27. Thus, a small amount ,of air can be caused to leak between the wall member 27 and the sleeve 63 from the outer passageway 29 into the inner passageway 44.

Accordingly, the combination fan construction ltlof this invention is not merely another dual fan construction having limited utility and restricted primarily to use for exchanging gas in, or Ventilating, the zone immediately adjacent the wall upon which the -fan construction is mounted. Applicants fan construction 10 is, on the contrary, -capable of a wide variety of uses wherein separate exhaust and supply units of the centrifugal type are presently used in order to provide both the capacity and the static pressures which are required, particularly where it is important to hold down the noise which is normally incident to the use of propeller-type fans for this purpose. In this regard, Vit will be observed that a typical, slow- `speed multi-blade centrifugal fan wheel will normally be used'in the fan construction 1t) where a Ventilating application is involved. Accordingly, the propeller fan which provides the supply air will also be operating at a relatively low tip speed which will not produce an objectionable noise. Moreover, since the propeller fan is shrouded by the casing 26 and used 4with guide vanes 95, such noise will be reduced additionally. Since the most efficient, outer portion of the propeller fan is being used in the impeller 12, adequate air movement will normally be provided as discussed above.

MODIFIED CONSTRUCTION The modified fan construction 110 (FIGURE 6) includes a housing 11a which, in general, is similar to the housing 11 in fan construction 10. That is, the housing 11a includes -an -outer casing 26a, a cylindrical wall member 27a, an impeller assembly 12a, a motor 13u, a motor cover 14a and a baffle assembly 74a, all of which may be substantially identical with their counterparts in the fan construction 10.

The fan construction 119 includes a plurality of adjustable inlet vanes 111 located in the inlet passageway 78a between the lower baflle ring 75a and the annular flange 25a on the casing 26a. Each inlet vane 111 is secured between two opposite edges thereof to a rod which is parallel with said edges and is pivotally supported near its opposite ends upon .said baille ring 75a and annular flange 25a. The lower end of each pivot rid 112 has an integral crank 113 which is engaged by the radial flange 114 which projects from a control ring 116 coaxially supported upon the outer casing 26a adjacent the flange 25a. A guide rail 117 is mounted upon the casing 26a for holding the control ring 116 in a selected position upon the casing 26a. With the inlet vanes 111 in their FIGURE 7 positions, the performance of the blades 64a of the axial flow fan 62a is substantially bet- Iter than its performance with the vanes 111 yat 90 degrees from their FIGURE 7'positions. The performance of the guide vanes 95a remains substantially the same in both cases.

The bearing assembly 119 is comprised of -a tube 120 which has a mounting flange 121 at its lower end for supporting said tube upon and above the upper wall 20a. A shaft 122 is supported within the tube 120 by the upper and lower bearings 123 and 124, respectively. The lower end of the shaft 122 extends through a central opening in the upper wall 20a and is received into and secured to the hub 48a, which is mounted upon the backplate 47a lof the centrifugal wheel 46a. The hub 48a may be the same as the hub 48, except that the hub 48a is mounted upon the opposite side of the backplate 47.

A driven pulley 87a is mounted upon the upper end of the shaft 122 and is connected to a driving pulley 91a which is mounted upon the motor shaft 88a. The motor 13a is mounted upon a motor pedestal 126 which is in turn supported upon the upper wall Ztla so that the motor shaft 38a extends upwardly. The bearing assembly 119 and most of the shaft 122 are disposed yabove the upper wall 20a within the motor cover 14a.

It will be seen from the foregoing description that, particularly where the limpeller assembly 12a is relatively small, the motor may be mounted upon theupper wall 20a so that the motor shaft 38a extends downwardly through the upper Wall 20a. In such case, the impeller assembly 12a can be mounted directly on the motor shaft so that no intermediate drive mechanism, including the shaft 122, will be required.

An inlet vane control 12S, having a central hub 129 from which `a plurality of radially disposed inlet vanes 130 extend, may be disposed within annulus or shroud 131 which is in turn connected to the lower end of and coaxial with the cylindrical wall member 27a. Thus, by appropriate movement of lthe inlet vanes 130 around their radial axes, in a well-known manner, the amount of gas moving through the cylindrical wall member 27a lcan be controlled, thereby controlling t-he amount of gas removed by the centrifugal Wheel 46a.

The operation of the modied fan construction will be substantially the same as the operation of the fan construction 10, subject to the variations discussed in the foregoing paragraphs.

Although particular preferred embodiments of the invention have been disclosed above in detail for illustrative purposes, it will be understood that variations or modifications of such disclosure, which come within the scope of the appended claims, are fully contemplated.

What is claimed is: 1. A gas moving apparatus, comprising: an outer casing having a portion of substantially circular cross section; a centrifugal impeller having an inlet side; shaft and bearing means secured with respect to said casing and rotatably supporting said irnpeller so that said irnpeller is substantially coaxial with, external of, and spaced from one end of said portion of circular cross section, said impeller having its inlet side gpposing said end of said portion and spaced thererom;

a -sleeve substantially coaxial with, and secured near one end thereof to, the inlet side of said impeller, said sleeve extending from said impeller toward said casing and being coaxial with said shaft and bearing means, said sleeve defining therewithin an inner passageway, and -said sleeve and said casing defining therebetween an outer passageway, rotation of said centrifugal impeller around the axis of said shaft effecting movement of gas axially along said inner passageway toward said impeller and radially away from said impeller;

a plurality of axial flow blades mounted upon said sleeve at intervals around the periphery thereof and spaced axially from said impeller, said lblades being arranged within said outer passageway so that said rotation of said impeller causes said blades to effect movement of gas axially along saidouter passageway away from said impeller; and

a plurality of guide varies disposed within and at intervals around said outer passageway near said axial flow blades, said vanes being mounted on and extending substantially radially inwardly from said casing a distance less than half the radial distance between said casing and said sleeve adjacent said varies.

2. A structure according to cl-airn 1 wherein the downstream ends of ysa-id vanes are substantially perpendicular to the rotation-al plane of said blades, and the upstream ends of said vanes are curved substantially around a radius of the casing and into the flow of gas from said blades.

3. A gas moving apparatus, comprising:

an outer casing having a portion of substantially circular cross section;

a centrifugal impeller having blades and an inlet side;

shaft and bearing means secured with respect to said casing and rotatably supporting said impeller s-o that said impeller is substantially coaxial with and spaced from one end of said portion of circular cross sec- Ition, said mpeller having its inlet side facing the interior of said portion and spaced from said end of said .port-ion;

a sleeve substantially coaxial with, and secured near one end thereof to, said impeller, said sleeve extending from said impeller into, and being of smaller diameter than, said portion of said casing and being coaxial with said shaft and bearing means, said sleeve defining therewithin an inner passageway, and said sleeve and said casing defining therebetween an outer passageway, rotation of said centrifugal impeller around the axis of said shaft effecting movement of gas axially along said inner passageway toward said impeller and radially away from said impeller;

a plurality `of axial flow blades mounted upon said sleeve at intervals around the periphery thereof and spaced axially from said impeller blades, said axial flow blades being arranged within said outer passageway so that said rotation of said impeller causes said axial iiow blades to effect movement of gas axially along said outer passageway away from said impelrler; and

a plurality of guide vanes disposed within and at uniform intervals a-round said outer passageway adjavcent the downstream sides of said axial flow blades, the downstream ends of said vanes being substantially perpendicular to the rotational plane of said blades, and the upstream ends of said vanes being curved substantially around a radius of the casing and into the flow of gas from said axial flow blades.

4. A gas moving apparatus, comprising:

an outer casing having a substantially cylindrical portion;

a centrifugal impeller havin-g an inlet side;

shaft and bearing means secured with respect to said casing and rotatably supporting said impeller so that said impeller is substantially coaxial with, and spaced from one end of, said cylindrical portion, said impeller having it-s inlet side facing the interior of said portion and spaced from said end of said portion;

a sleeve substantially coaxial with, and secured near one end thereof to, the Vinlet side of said impeller, said sleeve extending from said impe-ller toward said .portion of said casing and being coaxial with said shaft and bearing means, said sleeve defining there- 'within an inner passageway, and said sleeve and said casing deiiningtherelbetween an outer passageway, rotation of said centrifugal iympeller around the axis `of .said shaft effecting movement or" gas axially aiong said inner passageway toward said impeller and radially away from said inrpeller;

a plurality of axial flow blades mounted upon said sleeve at interval-s around the periphery thereof and spaced axially from said impeller, said blades being substantially wider adjacent said slee-ve than they are adjacent said casing and being twisted around their lengthwise axes in the right-hand direction, said blades being larranged within said outer passageway so that said rotation of said impeller causes said blades to effect movement of gas axially along said outer passageway away from said impel-ler.

5. A struct-ure accord-ing to claim 4 including a plurality of guide vanes disposed within and at uniform intervals around said outer passageway adjacent the downstream side of said axial orw blades, said guide vanes being secured to said casing and extending radially inwardly therefrom approximately half the radial distance between said sleeve and said casing.

6. A structure according to claim 4 wherein each axial flow blade is adjustably mounted upon said sleeve so that each blade can be adjusted around an axis extending radially of said portion of said casing.

7. A gas moving apparatus, comprising:

a substantially cylindrical outer casing;

a centrifugal impeller having an inlet side;

shaft and bearing means secured with respect to said casing and rotatably support-ing said .impeller sothat said impeller is substantially coaxial with, and spaced from one end of, said casing, said impeller having its inlet side facing the interior of said casing and spaced therefrom;

a sleeve substantially coaxial with, and secured near one end thereof to, the inlet side of said impeller, said sleeve extending from said impeller into, and bein-g of smaller diameter than, said casing and being coaxial with said shaft and bearing means, said sleeve defining therewithin an inner passageway, and said sleeve kand said casing defining therebetween an outer passageway, rotation of said centrifugal impeller around the axis of said shaft effecting movement of gas axially along said inner passageway toward said impelier and radially away from said impeller;

a plurality of axial iiow blades mounted upon said sleeve at intervals around the periphery thereof and l l. spaced axially from said impeller, said blades being arranged w-ithin said outer passageway so that said rotation of said impeller causes said blades to effect movement of gas axially along said outer passageway away from said impeller;

annular flange means secured to, and extending radially outwardly from, said .ca-sing adjacent the upstream end thereof;

a baille ring mounted upon said casing, said ring being spaced axially from said annular flange means and extending radially outwardly from near the inlet side of said impeller;

a plurality of inlet vanes pivotally supported upon and between said baffle ring and said annular flange means for pivotal movement around axes parallel vwith the axis of said shaft; and

`actuating means connected to each of said inlet vanes for controlling the movement and the position thereof.

. A gas moving apparatus, comprising:

an outer casing having a portion of substantially circular cross section;

a Vcentrifugal `impeller `having an inlet side;

shaft and bearing means secured with respect to said casing and rotatably supporting said impeller so that said impeller is substantially coaxial with, and spaced from one end of, said portion of circular cross section, said impeller having its inlet Side facing the interior of said portion and spaced from said end of said portion;

a sleeve substantially coaxial with, and secured near one end thereof to the inlet side olf said impeller, said sleeve extending from said impeller into, and 'being of smaller diameter than, said portion of said casing and being coaxial with said shaft a-nd bearing means, said sleeve defining therewithin an inner passageway, and said sleeve and said casing dening therebetween an outer passageway, rotation of said centrifugal impeller around the axis of said shaft effecting movement of gas axially along said inner passageway toward said impeller and radially away from said impeller;

a plurality of axial How blades mounted upon said sleeve at intervals around the periphery thereof and spaced axially from said impeller, said blades being arranged within said outer passageway so that said rotation of said impeller cau-ses said blades to effect movement of gas axially along said outer passageway substantially cylindrical wall means of approximately Vthe same diameter as, and coaxial with, said sleeve, said wall means extending from adjacent said sleeve axially away from said impeller; and

inlet vane control means mounted on said wall means at a point therein spaced from said sleeve for controlling the amount of air moving through said wall means and said sleeve.

9. A gas moving apparatus, comprising:

an outer casing having 'a portion of `substantially cir- -cular cross section;

a centrifugal impeller having an inlet on one axial side and a backplate on the opposite axial side;

yframe structure means secured to, and rigidly held with respect to, said casing near to and above said lbackplate of said impeller;

d-nive means, including shaft means and bearing means ysupported upon said frame structure principally above said impeller, said shaft means being secured near its lower end to said impeller and being rotatably supported by said bearing means 4coaxially with said portion of circular cross section, and motor means connected to said shaft means for rotating said impeller around an axis substantially coaxial with said portion of circular cross section, said impeller having its inlet side facing the interior lik l2. of said portion and being spaced from one end of said porton;

a sleeve substantally coaxial with, and secured near one end thereof to, the inlet side of Vsaid impeller, said sleeve extending from said impeller in-to, and

being of smaller diameter than, said portion of said casing and being coaxial with said shaft and bearing means, said sleeve defining therewithin an inner passageway, and said sleeve and said casi-ng defining therebetween an outer passageway, rotation of said centrifugal impeller around the axis of said shaft means effecting movement of gas axially along said 'inner passageway toward said impeller and radially away from said impeller;

a plurality of axial flow blades mounted upon said sleeve at intervals around the periphery thereof and spaced axially from said impeller, said blades being arranged within said portion of circular cross section so that said vnotation of said impeller causes said blades to effect movement of gas axially along said outer passageway, away from said impeller.

10. A structure according to claim 9 wherein said shaft means is an integral part of said motor means.

y11. A structure according to claim 9 wherein said shaft means is connected to said motor means by pulley and belt means.

12. A gas moving apparatus, comprising:

an outer casing having a portion of substantially circular cross section;

a centrifugal impeller having an inlet side;

shaft and bearing means secured with respect to said casing and rotatably supporting said impeller so that said impeller is substantially coaxial with, external of, and spaced from one end of said portion of circular cross section, said impeller ,having its inlet side opposing said end of said portion and spaced therefrom;

a sleeve substantially coaxial with, and secured near one end thereof to, the inlet side of said impeller, said sleeve extending from said impel-ler .toward said casing and .being coaxial with said shaft and bearing means, said sleeve `defining therewithin an inner passageway, and said sleeve a-nd said casing defining therebetween an outer passageway, rotation of said centrifugal impeller around the axis of said shaft effecting movement of gas axially along said inner passageway .toward said impeller and radially away from said impeller;

a plurality of axial llow blades mounted upon said sleeve at intervals .around the periphery thereof and spaced axially from said impeller, said blades being arranged within said outer passageway so that said rotation of said impeller causes said blades to effect movement of gas axial-ly along said outer passageway away from said impeller; and

a plurality of guide vanes disposed within and at intervals around said outer passageway near said axial iow blades, said vanes being mounted on and extending substantially radially inwardly from said 4ca-sing so that they are axially aligned with the circular path along which .the tip por-tions only of said blades move when said impeller is rotated.

References Cited by the Examiner UNITED STATES PATENTS Re. 20,668 3/38 Seelig 230--112 X 2,004,571 6/35 BotheZat -230--1-17 2,371,706 3/45 Planiol 230--122 X 2,844,001 7/58 Alford 230--1-34 3,122,307 2/64 Wasson et al. 230-117 LAURENCE V. EFNE'R, Primary Examiner.

ROBERT M, WALKER, Examiner. 

1. A GAS MOVING APPARATUS, COMPRISING: AN OUTER CASING HAVING A PORTION OF SUBSTANTIALLY CIRCULAR CROSS SECTION; A CENTRIFUGAL IMPELLER HAVING AN INLET SIDE; SHAFT AND BEARING MEANS SECURED WITH RESPECT TO SAID CASING AND ROTATABLY SUPPORTING SAID IMPELLER SO THAT SAID IMPELLER IS SUBSTANTIALLY COAXIAL WITH, EXTERNAL OF, AND SPACED FROM ONE END OF SAID PORTION OF CIRCULAR CROSS SECTION, SAID IMPELLER HAVING ITS INLET SIDE OPPOSING SAID END OF SAID PORTION AND SPACED THEREFROM; A SLEEVE SUBSTANTIALLY COAXIAL WITH, AND SECURED NEAR ONE END THEREOF TO, THE INLET SIDE OF SAID IMPELLER, SAID SLEEVE EXTENDING FROM SAID IMPELLER TOWARD SAID CASING AND BEING COAXIAL WITH SAID SHAFT AND BEARING MEANS, SAID SLEEVE DEFINING THEREWITHIN AN INNER PASSAGEWAY, AND SAID SLEEVE AND SAID CASING DEFINING THREBETWEEN AN OUTER PASSAGEWAY, ROTATION OF SAID CENTRIFUGAL IMPELLER AROUND THE AXIS OF SAID SHAFT EFFECTING MOVEMENT OF GAS AXIALLY ALONG SAID INNER PASSAGEWAY TOWARD SAID IMPELLER AND RADIALLY AWAY FROM SAID IMPELLER; A PLURALITY OF AXIAL FLOW BLADES MOUNTED UPON SAID SLEEVE AT INTERVALS AROUND THE PERIPHERY THEREOF AND SPACED AXIALLY FROM SAID IMPELLER, SAID BLADES BEING ARRANGED WITHIN SAID OUTER PASSAGEWAY SO THAT SAID ROTATION OF SAID IMPELLER CAUSES SAID BLADES TO EFFECT MOVEMENT OF GAS AXIALLY ALONG SAID OUTER PASSAGEWAWY AWAY FROM SAID IMPELLER; AND A PLURALITY OF GUIDE VANES DISPOSED WITHIN AND AN INTERVALS AROUND SAID OUTER PASSAGEWAY NEAR SAID AXIAL FLOW BLADES, SAID VANES BEING MOUNTED ON AND EXTENDING SUBSTANTIALLY RADIALLY INWARDLY FROM SAID CASING A DISTANCE LESS THAN HALF THE RADIAL DISTANCE BETWEEN SAID CASING AND SAID SLEEVE ADJACENT SAID VANES. 